Brain tumors are the second most common type of cancer in children, affecting approximately one in every 30,000-40,000 children in the U.S. (Singer &Byrne, n.d.). Neurocognitive deficits are common late effect of treatment, evident along cognitive and quality of life (QOL) domains. The overall objective of this study is to determine whether children treated with high-dose chemotherapy with autologous hematopoietic progenitor cell rescue (AuHCR) for medulloblastoma or ependymoma will display key areas of white matter and gray matter injury from this treatment, which results in deficits in cognitive functioning and decreased quality of life (QOL). Age at diagnosis and gender, both critical predictors of neurocognitive outcome in children with brain tumors, will be considered by limiting the sample to males and exploring age at diagnosis as a covariate. Specific aims of this study are 1) using diffusion tensor imaging (DTI) techniques, assess gray and white matter tissue injury in regions of interest in boys treated for medulloblastoma or ependymoma with high-dose chemotherapy with AuHCR 6-36 months prior in comparison to age'-matched healthy controls, and;2) evaluate the relationship between gray and white matter tissue injury in cognitive centers in the brain and functional outcomes (cognitive, QOL) in boys treated with high-dose chemotherapy with AuHCR 6-36 months prior. This study will utilize a 2-group quasi-experimental design with 23 male children 5-8 years of age in each group for specific Aim 1. Injury caused by high-dose chemotherapy to white and gray matter in childhood brain tumor survivors as measured by fractional anisotropy and median diffusivity will be compared to healthy controls, with age at diagnosis as a covariate. For Aim 2, this will be a survey design, using a single sample of the subject group only. White and gray matter volume loss in the brain will be explored as predictors of neuropsychological findings in the areas of memory and executive function and QOL. All subjects in the experimental group will undergo DTI as part of their routine follow-up MRI. About 2/3 of children with brain tumors survive their cancer and live to adulthood. However, the majority of children are left with some type of cognitive deficit causing problems with memory and higher executive functioning. Many children have learning disabilities and low IQs, leading to lower educational attainment, higher likelihood of unemployment, lower rates of marriage and parenthood and higher rates of divorce and interpersonal relationship problems. All of these issues negatively affect quality of life, and lead to increased need for utilization of health care resources and social services.